Pollution
Humain
Environnement
Economique

In a chlorochemical plant, a retention basin of a 200 m³ ferric chloride tank was being drained into an empty intermediate bulk container (IBC) so that a leaky tank valve could be replaced. The tank expanded and overflowed 20 seconds after the draining operation began. Chlorine vapours were released and three employees in a radius of 10 meters were overcome by the fumes (irritation of the respiratory tract and the eyes). The injured were examined in the infirmary and then returned to work.

The empty IBC, recovered from a solid ferric chloride storage warehouse, had previously contained bleach. The bleach violently reacted with the diluted ferric chloride resulting in the release of chlorine gas in concentrations estimated between 5 and 10 ppm (the Cl2 sensors located 60 m away detected 1.8 ppm).

The operator set up a colour coding system to identify the tanks used on the site and a procedure for managing reusable IBCs. The used containers available for reuse are stored in a locked area and non-compliant containers are destroyed. A program has been set up to raise the awareness of personnel as to the risks of incompatible mixtures (safety bulletins, annual training, etc.).